Nanofiltration membrane

Abstract

Asymmetric integrally-skinned PAEK nanofiltration membranes suitable for nanofiltration of an organic solvent feed stream are disclosed, together with their uses in organic solvent nanofiltration, and their methods of preparation. Membranes are prepared from phase inversion processes and are then subjected to a post-manufacturing heat treatment step in order to arrive at molecular weight cut off characteristics within the nanofiltration region. The membranes exhibit stability over a wide range of p H and temperature.

1 . An asymmetric integrally-skinned nanofiltration membrane comprising a PAEK polymer, wherein the membrane has a degree of sulphonation of less than 40% and is suitable for performing nanofiltration in a polar aprotic organic solvent. 
     
     
         2 . The membrane of  claim 1 , wherein the PAEK polymer is selected from the group consisting of PEK and PEEK. 
     
     
         3 . The membrane of  claim 1 , wherein the PAEK polymer is PEEK. 
     
     
         4 . The membrane of  claim 1 , wherein the membrane has a degree of sulphonation of less than 30%. 
     
     
         5 . The membrane of  claim 1 , wherein the membrane has a degree of sulphonation of less than 10%. 
     
     
         6 . The membrane of  claim 1 , wherein the membrane has a degree of sulphonation of less than 8% 
     
     
         7 . The membrane of  claim 1 , wherein the membrane has a molecular weight cut off of 100-1000 g mol-1. 
     
     
         8 . The membrane of  claim 1 , wherein the membrane has a molecular weight cut off of 200-750 g mol-1. 
     
     
         9 . The membrane of  claim 1 , wherein the membrane has a molecular weight cut off of 400-600 g mol-1. 
     
     
         10 . The membrane of  claim 1 , wherein the membrane has a permeance of 0.02-10 L h-1 m-2 bar-1. 
     
     
         11 . The membrane of  claim 1 , wherein the membrane has a permeance of 0.05-0.9 L h-1 m-2 bar-1. 
     
     
         12 . The membrane of  claim 1 , wherein the membrane has a permeance of 0.07-0.8 L h-1 m-2 bar-1. 
     
     
         13 . The membrane of  claim 1 , wherein the PAEK polymer has a molecular weight of 25-60 kDa. 
     
     
         14 . The membrane of  claim 1 , wherein the PAEK polymer has a molecular weight of 30-55 kDa. 
     
     
         15 . The membrane of  claim 1 , wherein the membrane further comprises a conditioning agent. 
     
     
         16 . The membrane of  claim 15 , wherein the conditioning agent is a low volatility organic liquid. 
     
     
         17 . The membrane of  claim 15 , wherein the conditioning agent comprises at least one compound selected from the group consisting of synthetic oils, mineral oils, vegetable fats and oils, higher alcohols, glycerols and glycols. 
     
     
         18 . The membrane of  claim 15  wherein the conditioning agent is polyethylene glycol or silicone oil. 
     
     
         19 . The membrane of  claim 1 , wherein the membrane has a thickness of 30-300 μm. 
     
     
         20 . A process for the preparation of a membrane according to any preceding claim, the process comprising the steps of:
 a) preparing a polymer solution comprising a solubilised PAEK polymer,   b) casting the polymer solution onto a support,   c) performing phase inversion of the cast polymer solution, and   d) exposing the resulting membrane to a temperature of 20-200° C.   
     
     
         21 .- 49 . (canceled)